The primary goal of this research is to elucidate the mode of binding to deoxyribonucleic acid (DNA) of several cancerostatic antibiotics in current or prospective use (mithramycin, chromomycin, luteoskyrin). The unifying theme of this work is that the drugs proposed bind to DNA only in the presence of divalent metal ions. As of this date, the exact function of these ions, and the structural characteristics of this mode of ion-dependent binding, are not known. By this proposed study of structure and mode of antibiotic binding to DNA, we should be able to understand the function of the metal ion in binding, and aspects of the stereochemistry of the bound complex. These details will reflect the attractive forces holding together what is an important and little understood complex of DNA. These problems are particularly susceptible to solution by nuclear magnetic resonance (NMR) techniques. We consider only paramagnetic ions because their strong magnetic interactions with nuclei perturb the NMR parameters in ways that can be interpreted quantitatively. In this NMR study, the nature of the interactions of metal ions with antibiotics and the location of binding sites will be elucidated by temperature, pH, and concentration studies.